Optimize Session Startup by Parallelizing Component Initialization

[golbin]

Description

Is this reporting a bug or feature request?
This is a feature request to optimize the session startup process.

Issue description

The current session startup process initializes components (TTS, LLM, STT, and Daily Join) sequentially, which results in higher latency before the session becomes operational. By refactoring the process to initialize these components in parallel, the startup time can be significantly reduced.

Expected behavior

The initialization of TTS, LLM, STT, and Daily Join should occur in parallel, resulting in a noticeable reduction in session startup time.

[aconchillo]

Thank you for reporting this @golbin . The reason behind the current behavior is to make sure all the components are successfully initialzed in order so we don't push frames prematurely. But yes, maybe we could possibly initialize everything in parallel and just wait for the last service being initialized before starting pushing frames.

[golbin]

Always thank you @aconchillo 🙂

Yes, handling parallel processing might be a bit challenging, but it could significantly reduce the startup time.

If we can reuse a bot process, the startup could become extremely fast. Additionally, if we can maintain connections to TTS and STT even after the session ends, we could potentially onboard new users with almost no waiting time.

For a simpler approach, we could start by parallelizing only the Daily transport and joining. This alone could substantially reduce the waiting time.

Time	Event	Time Difference
2024-12-21 10:36:27.580	Modules: Session started	0.001 seconds
2024-12-21 10:36:27.580	VAD: Set VAD parameters	0.000 seconds
2024-12-21 10:36:27.649	Audio: Silero VAD loaded	0.069 seconds
2024-12-21 10:36:27.684	Processors: Link frame processors	0.035 seconds
2024-12-21 10:36:27.909	Services: Connect to Cartesia	0.225 seconds
2024-12-21 10:36:28.178	Daily: Join session	0.269 seconds
2024-12-21 10:36:28.616	Daily: Joined session	0.438 seconds
2024-12-21 10:36:29.042	Modules: Sync session state	0.426 seconds
2024-12-21 10:36:29.043	Modules: Update session state	0.001 seconds
2024-12-21 10:36:30.132	Daily: Participant joined	1.089 seconds
2024-12-21 10:36:30.133	Modules: Participant joined session	0.001 seconds
2024-12-21 10:36:30.334	Pipeline: Start session with greeting	0.201 seconds
2024-12-21 10:36:30.335	Cartesia: Generate TTS for greeting	0.001 seconds
2024-12-21 10:36:30.508	Bot: Started speaking	0.173 seconds